Pipe Threading
- Thread starter huffdawg
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heaterman
Minister of Fire
North of 60
Minister of Fire
Up to 2" pipe allow for 5/8 engagement/thread purchase.. Figure it out so you know what it is from center of the fitting to the engagement and subtract that for your end to end measurement of your pipe. Lay all your work out using pipe centers.
ewdudley
Minister of Fire
huffdawg said:
Google:
pipe thread engagement chart
I found that when they say maximum they mean awfully tight. Maximum minus about 3/32"/0.100"/2.5mm seemed to work for me for 1/2" through 2".
If you're doing really fine work Loctite 55 pipe sealing cord can give you that half turn of fudge factor you may need to have things come out perfectly.
Also, knowing nothing about the bucket of salvage pump flanges I was working with, there seemed to be some that were straight threads or something, which definitely need the pipe sealing cord to prevent excess engagement in past the inner face of the flange.
--ewd
Given the variable quality of fittings and threads it can also be useful to use a couple of short nipples (if you have the room) and use them as gages
Clean up the threads with a triangle file and clean the crud out of them. Turn the nipples into the same fittings that you will use and snug them up, but not enough to make it difficult to get them out again. Layout the fittings at the proposed spacing or even in the actual location and measure the distance between the ends of the gage nipples. Add the length of the two gage nipples and the distance between them and add a thread length for the extra muscle you'll put on them when tightening for real. That will get pretty close, too.
Clean up the threads with a triangle file and clean the crud out of them. Turn the nipples into the same fittings that you will use and snug them up, but not enough to make it difficult to get them out again. Layout the fittings at the proposed spacing or even in the actual location and measure the distance between the ends of the gage nipples. Add the length of the two gage nipples and the distance between them and add a thread length for the extra muscle you'll put on them when tightening for real. That will get pretty close, too.
ewdudley said:
The straight threads might of been British Standard Pipe threads? I was reading in some other posts about using the cord and I looked all over town and nobody sells it here not even the plumbing wholesaler. So I have been using 1" teflon tape and the blue thread sealing compound.
Thanx
Huff
We assemble a lot of straight BSP threads. Clean them with a fitting brush first, inside and outside threads. We use red Loctite 525 for all of our assembly. What is nice about straight threads is you can stop anywhere to get the correct "take up" length. As long as you have 3 or so threads in the fitting.
If you need to disassemble a Loctite threaded fitting heat it with a torch until you smell the Loctite cooking and it easily un-threads. Not much heat is needed.
I would guess Loctite would work on tapered threads also, but it is expensive and and overkill for a tapered thread.
hr
If you need to disassemble a Loctite threaded fitting heat it with a torch until you smell the Loctite cooking and it easily un-threads. Not much heat is needed.
I would guess Loctite would work on tapered threads also, but it is expensive and and overkill for a tapered thread.
hr
salecker
Minister of Fire
Hi
When i started building my system,the owner of the plumbing store i'm getting my supplies from told me to use Hemp on all my pipe threads.He said if used properly it will not leak.
Proper prep is to take a sharp center punch and score the threads on the male fitting at a 90 degree from the threads.Score them as deep as yopu can by hand,this gives the hemp something to grab as you are threading them together.Wrap the hemp in the same direction as you would use tape.Wrap enough to cover the threads and use your hand to twist it into the threads.Then use a good quality pipe dope to cover the hemp.Tighten as ussual.
I was a bit sceptic at first.So i tried a comparison when i tested my tanks.
!st tank i installed all perment plugs with hemp and dope.Used teflon tape on the temp plugs and fill/gage.All the teflon joints leaked,really had to tighteen them hard to get them to slow down,one never sealled completely.
2nd tank,perment plugs hemp and dope,temperary plugs just dope,same thing the temp plugs needed more force to stop weeping,all plugs that had the hemp and dope on both tanks were leak free/
I had to retest the first tank,due to a bad weld.The last test i used hemp and dope on the temerary plugs and they were leak free.
so far i'm guessing i have close to 70 threaded joints in my system,have not had any leaks on any threaded joints,has been holding 65 PSI for over a week.
It takes a little extra time to do the prep,but well worth it for no leaks.
He did also say that if you did have a leak as soon as any liquid gets to the hemp it swells and seals the joint.Works for all liquids.He qurenteed if done to these conditions there would be no leaks
Now i'm a hemp user,have eveb stared using it on all my trucks and equipment when i takeapart a threaded fitting.
Hope someone gets some use from this
Thomas
When i started building my system,the owner of the plumbing store i'm getting my supplies from told me to use Hemp on all my pipe threads.He said if used properly it will not leak.
Proper prep is to take a sharp center punch and score the threads on the male fitting at a 90 degree from the threads.Score them as deep as yopu can by hand,this gives the hemp something to grab as you are threading them together.Wrap the hemp in the same direction as you would use tape.Wrap enough to cover the threads and use your hand to twist it into the threads.Then use a good quality pipe dope to cover the hemp.Tighten as ussual.
I was a bit sceptic at first.So i tried a comparison when i tested my tanks.
!st tank i installed all perment plugs with hemp and dope.Used teflon tape on the temp plugs and fill/gage.All the teflon joints leaked,really had to tighteen them hard to get them to slow down,one never sealled completely.
2nd tank,perment plugs hemp and dope,temperary plugs just dope,same thing the temp plugs needed more force to stop weeping,all plugs that had the hemp and dope on both tanks were leak free/
I had to retest the first tank,due to a bad weld.The last test i used hemp and dope on the temerary plugs and they were leak free.
so far i'm guessing i have close to 70 threaded joints in my system,have not had any leaks on any threaded joints,has been holding 65 PSI for over a week.
It takes a little extra time to do the prep,but well worth it for no leaks.
He did also say that if you did have a leak as soon as any liquid gets to the hemp it swells and seals the joint.Works for all liquids.He qurenteed if done to these conditions there would be no leaks
Now i'm a hemp user,have eveb stared using it on all my trucks and equipment when i takeapart a threaded fitting.
Hope someone gets some use from this
Thomas
ewdudley
Minister of Fire
huffdawg said:
I got the cord through Grainger, but I only needed it for those odd pump flanges I mentioned and for fitting three parallel cross-rungs of a piping ladder where two pumps and a union all had be adjusted to fit up simultaneously just-so. The loctite stuff mentioned below sounds like it would be better and quicker.
For anything else black permatex pipe dope; teflon tape; rectorseal 5 dope; or teflon tape plus rectorseal 5 dope all worked equally as well for me.
woodsmaster
Minister of Fire
salecker said:
When I went to the plumbing supply store they looked at me like I was from mars when I asked about the cord. I thought of getting some hemp black market , but went with teflone tape and haveys teflone pipe dope instead.
no leaks !
Im having toubles with the threader binding when I back it off the the threads , it then wrecks the threads I just cut. Any hints would be appreciated.
huffdawg said:
Could be you over-tightened it. Then the threads pull, or rip and gaul up inside the fitting. Or poor quality steel that tears when you thread it?
hr
I only threaded till the last cutter was past the end of the pipe. I also watched the wholesaler thread the same pipe on a mechanical threader with no problems.in hot water said:
I will try running the die onto a precut nipple and adjusting the cutters.
ewdudley
Minister of Fire
huffdawg said:
For me three things seemed to help.
The most important was luck. I found the best time not to have bad luck was at the end of the second thread on a 2" nipple.
The next thing was to go clockwise a third or a half of a full turn, then use a small flux brush or whatever to paint everything with a little cutting oil, then reverse the threader a quarter turn or so, paint again, and proceed for another third or a half turn of progress past where you were before the reverse.
The third thing was beer. If you tend to be a little too fussy, ingestion of a little beer, but not too much, can be just what it takes to lower your standards somewhat to the point where you're willing to accept some imperfections. That and a light coating of the black tarry Permatex pipe compound on both the male and female threads can work miracles towards rehabilitating some pretty nasty looking threads.
Cheers --ewd
Use real thread cutting oil, not just motor oil. It will usually smell sulfurous, like rotten eggs.
You need to use lots of oil continuously as you cut the thread over all the teeth that are cutting. Watch the motorized threaders. They have a constant flow of oil over the area being cut. Like hot rod says, the metal may be tearing as you cut, and only becoming noticeable when you try to back out.
Dull dies are next on the list of causes.
You need to use lots of oil continuously as you cut the thread over all the teeth that are cutting. Watch the motorized threaders. They have a constant flow of oil over the area being cut. Like hot rod says, the metal may be tearing as you cut, and only becoming noticeable when you try to back out.
Dull dies are next on the list of causes.
The dies are brand new and the oil is the Rigid premium Nu-Clear pipe threading oil. But I am, pretty good at drinking beer. I,ll step it up a notch Eliot.
I talked to an old friend of mine that worked in a shipyard many years ago when most of the pipe cutting was done with elbow grease. He said to give the pipe a good wack with a ball peen hammer every couple turns it will knock
the cuttings out.
Thank you everyone for the tips
I talked to an old friend of mine that worked in a shipyard many years ago when most of the pipe cutting was done with elbow grease. He said to give the pipe a good wack with a ball peen hammer every couple turns it will knock
the cuttings out.
Thank you everyone for the tips
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